In January 1999, the NHLBI created a federally sponsored clinical research program to study childhood asthma and competitively selected 5 academic Clinical Centers and a Data Coordinating Center to participate in the Childhood Asthma Research and Education (CARE) Network that began work in September 1999. The CARE Network successfully initiated four clinical trials: (1) a long-term early secondary asthma prevention intervention protocol entitled Prevention of Early Asthma in Kids (PEAK); (2) a protocol to characterize the response to a leukotriene antagonist and an inhaled corticosteroid (CLIC); (3) a protocol to compare head-to-head the efficacy of three controller treatment regimens for persistent asthma [Pediatric Asthma Controller Trial (PACT)]; and (4) a protocolto evaluate two different acute intervention management strategies (AIMS) for young children with recurrent episodes of wheezing associated with significant morbidity. The application submitted by the CARE Network Clinical Centers (CCs) presents how the CARE Network has established a successful infrastructure to conduct clinical research, reviews progress made with the currently conducted and/or completed trials, and presents three sample protocols (BADGRE, PATO, and MAXISA) that the CARE Network considers to be of sufficient scientific merit to warrant renewed funding for an additional five years. This application submitted by the CARE Network Data Coordinating Center (DCC) describes the function and activities of the DCC. The six specific aims of the DCC are as follows: (1) provide biostatistical leadership and scientific coordination for the CARE Network, such as optimizing trial designs for increased accuracy and precision, projecting sample sizes, selecting and implementing randomization schemes, analyzing data, developing presentations/publications, preparing and leading training sessions, establishing certification criteria, writing the Manuals of Operations (MOPs), collaborating on recruitment/retention strategies, and resolving questions from the CCs; (2) establish and maintain the CARE Network computer network and website; (3) design and maintain the CARE Network data management system based on a wide-area network and world-wide web implementation; (4) develop and maintain the CARE Network data quality assurance and monitoring program, such as developing high-quality data collection forms, MOPs, and subject handouts, training and certifying CC staff in all CARE Network procedures and clinical trials, supporting CC staff during the conduct of CARE Network trials, and performing site visits and data audits; (5) provide project management and administrative support for the CARE Network; (6) provide oversight and management of data acquisition from biological samples.